Why is studying twins valuable when considering behaviors or diseases?

Why does the sun appear to be the brightest star in the sky? a- its apparent brightness is much greater than other stars. b- it burns more gas, making it brighter than any other star. c- it is the largest star in the galaxy, so it is the brightest star. d- its relative distance to earth is closer than the other stars.

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

To find the enthalpy of a reaction in the lab, you measured the of the reactants and the change during the reaction.